Conventionally, in a vehicle such as an automobile, in order to supply a power source such as a battery to various loads such as lights and motors, electric wires are used to connect the power source with each load. Due to vibrations caused by a traveling vehicle, these electric wires may contact a portion of a vehicle body. Furthermore, when the insulation coatings of the electric wires are damaged due to this contact, there is a possibility that an electrical short circuit or a current leak may be generated with the vehicle body. Such a current leak or full short circuit may cause the temperature of the damaged portion to increase, and insulation coatings may eventually emit smoke.